8. Serena Williams

Total earnings: $28.9 million

Prize money: $8.9 million

Endorsements: $20 million

Williams has paired with sister Venus to win three Olympic gold medals in doubles and both have won gold in singles. Williams tied the modern-day record at Wimbledon with her 22nd Grand Slam title in singles. Her endorsement portfolio includes more than a dozen brands like Nike, Chase, IBM, Delta Air Lines, Wilson and Beats.